Radiation detector, radiographic imaging apparatus, and method of manufacturing radiation detector

ABSTRACT

The radiation detector includes a sensor substrate and a reinforcing substrate. In the s sensor substrate, a plurality of pixels for accumulating electric charges generated in response to radiation is formed in a pixel region of a first surface of a flexible base material. The reinforcing substrate is provided on at least one of the first surface side of the base material or a second surface side opposite to the first surface, includes the foamed body layer, and reinforces the stiffness of the base material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/JP2021/006937, filed Feb. 24, 2021, the disclosureof which is incorporated herein by reference in its entirety. Further,this application claims priority from Japanese Patent Application No.2020-038170, filed on Mar. 5, 2020, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a radiation detector, a radiographicimaging apparatus, and a method of manufacturing the radiation detector.

2. Description of the Related Art

In the related art, radiographic imaging apparatuses that performradiographic imaging for medical diagnosis have been known. A radiationdetector for detecting radiation transmitted through a subject andgenerating a radiographic image is used for such radiographic imagingapparatuses.

As the radiation detector, there is one comprising a conversion layer,such as a scintillator, which converts radiation into light, and asubstrate in which a plurality of pixels, which accumulate electriccharges generated in response to light converted in the conversionlayer, are provided. As the base material of a sensor substrate of sucha radiation detector, one formed of a flexible base material is known.Additionally, by using the flexible base material, there is a case wherethe weight of the radiographic imaging apparatuses can be reduced andimaging of the subject becomes easy.

Meanwhile, in a case where a load, an impact, or the like is applied toa radiographic imaging apparatus, the substrate using the flexible basematerial is easily deflected. Therefore, in order to suppress theinfluence of the impact or the like on the radiation detector, thetechnique of increasing the bending stiffness of the radiation detectoris known.

For example, JP2012-173275A describes a technique of providing areinforcing member on a side, opposite to a scintillator side, of a thinfilm unit that detects fluorescence as an electrical signal.Additionally, for example, JP2014-081363A describes a technique ofbonding a reinforcing substrate to a radiation incidence side of aphotoelectric conversion panel or a side opposite to the radiationincidence side.

SUMMARY

Although the techniques described in JP2012-173275A and JP2014-081363Acan increase the bending stiffness of the radiation detectors asdescribed above However, there is a case where heat is non-uniformlytransferred to the pixel region provided with the pixels of eachradiation detector, and thereby, the image quality of a radiographicimage obtained by the radiation detector deteriorates.

The present disclosure provides a radiation detector, a radiographicimaging apparatus, and a method of manufacturing a radiation detectorhaving high bending stiffness and improved heat resistance.

A radiation detector of a first aspect of the present disclosurecomprises a substrate in which a plurality of pixels for accumulatingelectric charges generated in response to radiation are formed in apixel region on a first surface of a flexible base material; and areinforcing substrate that is provided on at least one of the firstsurface side of the base material or a second surface side opposite tothe first surface and include a foamed body layer to reinforce astiffness of the base material.

Additionally, a radiation detector of a second aspect of the presentdisclosure is the radiation detector of the first aspect in which thefoamed body layer is a resinous layer having a closed cell structure.

Additionally, a radiation detector of a third aspect of the presentdisclosure is the radiation detector of the first or second aspect inwhich the foamed body layer has a closed cell rate of 85% or more.

Additionally, a radiation detector of a fourth aspect of the presentdisclosure is the radiation detector of any one of the first to thirdaspects in which an average cell diameter of closed cells included inthe foamed body layer is 10 μm or less.

Additionally, a radiation detector of a fifth aspect of the presentdisclosure is the radiation detector of any one of the first to fourthaspects in which the foamed body layer has a multilayer structure inwhich a foam layer and a non-foam layer are laminated in a laminationdirection in which the substrate and the reinforcing substrate arelaminated.

Additionally, a radiation detector of a sixth aspect of the presentdisclosure is the radiation detector of the fifth aspect in which themultilayer structure is a sandwich structure in which the foam layer issandwiched between the non-foam layers.

Additionally, a radiation detector of a seventh aspect of the presentdisclosure is the radiation detector of the fifth or sixth aspect inwhich a main component of a material of the foam layer and a maincomponent of a material of the non-foam layer are the same.

Additionally, a radiation detector of an eighth aspect of the presentdisclosure is the radiation detector of any one of the first to seventhaspects in which the foamed body layer has a material containing atleast one of foamed styrene, foamed poly ethyleneterephthalate (PET), orfoamed polycarbonate as a main component.

Additionally, a radiation detector of a ninth aspect of the presentdisclosure is the radiation detector of any one of the first to eighthaspects in which the reinforcing substrate further includes a rigidplate that is provided on at least one surface of a surface of thefoamed body layer on a substrate side or a surface opposite to thesubstrate and has a bending elastic modulus higher than that of thefoamed body layer.

Additionally, a radiation detector of a tenth aspect of the presentdisclosure is the radiation detector of the ninth aspect in which athickness of the foamed body layer is larger than a thickness of therigid plate.

Additionally, a radiation detector of an eleventh aspect of the presentdisclosure is the radiation detector of the ninth or tenth aspect inwhich a main component of a material of the rigid plate is carbon fiberreinforced plastic (CFRP).

Additionally, a radiation detector of a twelfth aspect of the presentdisclosure is the radiation detector of any one of the ninth to eleventhaspects in which the rigid plate has a punching structure having aplurality of holes.

Additionally, a radiation detector of a thirteenth aspect of the presentdisclosure is the radiation detector of any one of the first to twelfthaspects further comprising an electromagnetic shield layer provided onthe second surface side of the base material.

Additionally, a radiation detector of a fourteenth aspect of the presentdisclosure is the radiation detector of any one of the first tothirteenth aspects further comprising an antistatic layer provided onthe second surface side of the base material.

Additionally, a radiation detector of a fifteenth aspect of the presentdisclosure is the radiation detector of the fourteenth aspect in whichthe antistatic layer is a laminated film of a resin film and a metalfilm.

Additionally, a radiation detector according to a sixteenth aspect ofthe present disclosure is the radiation detector according to any one ofthe first to fifteenth aspects further comprising a conversion layerthat is provided on the first surface of the base material to convertthe radiation into light. The pixels accumulate electric chargesgenerated in response to the light converted by the conversion layer.The reinforcing substrate is provided on at least one of a surface ofthe conversion layer opposite to a surface on a base material side orthe second surface side.

Additionally, a radiographic imaging apparatus according to aseventeenth aspect of the present disclosure comprises a radiationdetector of the present disclosure; and a circuit unit for reading outthe electric charges accumulated in the plurality of pixels.

Additionally, a method of manufacturing a radiation detector accordingto an eighteenth aspect of the present disclosure comprises a step ofproviding a flexible base material on a support body and forming asubstrate in which a plurality of pixels that accumulate electriccharges generated in response to radiation are provided in a pixelregion of a first surface of the base material; a step of providing areinforcing substrate that is provided on at least one of a firstsurface side of the base material or a second surface side opposite tothe first surface and include a foamed body layer to reinforce astiffness of the base material; and a step of peeling the substrate fromthe support body.

Additionally, a method of manufacturing a radiation detector accordingto an eighteenth aspect of the present disclosure is the method ofmanufacturing a radiation detector according to the nineteenth aspect inwhich the step of peeling the substrate is performed after the step ofproviding the reinforcing substrate on the first surface side of thebase material.

According to the present disclosure, the bending stiffness is high andthe heat resistance can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments according to the technique of the presentdisclosure will be described in detail based on the following figures,wherein:

FIG. 1 is a block diagram showing an example of the configuration ofmajor parts of an electrical system in a radiographic imaging apparatusof an embodiment,

FIG. 2 is a plan view of an example of a radiation detector according tothe embodiment as seen from a first surface side of a base material,

FIG. 3 is a cross-sectional view taken along line A-A of an example ofthe radiation detector shown in FIG. 2 ,

FIG. 4 is a cross-sectional view of an example of a reinforcingsubstrate including a foamed body layer of the embodiment,

FIG. 5 is a cross-sectional view for explaining a foamed body,

FIG. 6A is a cross-sectional view of an example of a reinforcingsubstrate including a foamed body layer having a multilayer structurecomposed of a foam layer and a non-foam layer of the embodiment,

FIG. 6B is a cross-sectional view of another example of the reinforcingsubstrate including the foamed body layer having the multilayerstructure composed of the foam layer and the non-foam layer of theembodiment,

FIG. 7A is a cross-sectional view of an example of the radiographicimaging apparatus according to the embodiment,

FIG. 7B is a cross-sectional view of an example of the radiographicimaging apparatus according to the embodiment,

FIG. 8A is a view for explaining an example of a method of manufacturingthe radiographic imaging apparatus of the embodiment,

FIG. 8B is a view for explaining an example of the method ofmanufacturing the radiographic imaging apparatus of the embodiment,

FIG. 8C is a view for explaining an example of the method ofmanufacturing the radiographic imaging apparatus of the embodiment,

FIG. 8D is a view for explaining an example of the method ofmanufacturing the radiographic imaging apparatus of the embodiment,

FIG. 8E is a view for explaining an example of the method ofmanufacturing the radiographic imaging apparatus of the embodiment,

FIG. 9A is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of the embodiment,

FIG. 9B is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of the embodiment,

FIG. 9C is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of the embodiment,

FIG. 9D is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of the embodiment,

FIG. 10 is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of the embodiment,

FIG. 11A is a cross-sectional view taken along line A-A of an example ofa radiation detector of Modification Example 1,

FIG. 11B is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of Modification Example 1,

FIG. 11C is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of Modification Example 1,

FIG. 11D is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of Modification Example 1,

FIG. 11E is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of Modification Example 1,

FIG. 12A is a cross-sectional view taken along line A-A of an example ofa radiation detector of Modification Example 2,

FIG. 12B is a cross-sectional view taken along line A-A of anotherexample of a radiation detector of Modification Example 2,

FIG. 13 is a cross-sectional view taken along line A-A of an example ofa radiation detector of Modification Example 3,

FIG. 14A is a cross-sectional view of an example of a radiographicimaging apparatus of Modification Example 4,

FIG. 14B is a cross-sectional view of another example of theradiographic imaging apparatus of Modification Example 4,

FIG. 14C is a cross-sectional view of still another example of theradiographic imaging apparatus of Modification Example 4, and

FIG. 14D is a cross-sectional view of still another example of theradiographic imaging apparatus of Modification Example 4.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the drawings. In addition, the presentembodiments do not limit the present disclosure.

The radiation detector of the present embodiment has a function ofdetecting radiation transmitted through a subject to output imageinformation representing a radiographic image of the subject. Theradiation detector of the present embodiment comprises a sensorsubstrate and a conversion layer that converts radiation into light(refer to a sensor substrate 12 and a conversion layer 14 of theradiation detector 10 in FIG. 3 ). The sensor substrate 12 of thepresent embodiment is an example of a substrate of the presentdisclosure.

First, the outline of an example of the configuration of an electricalsystem in a radiographic imaging apparatus of the present embodimentwill be described with reference to FIG. 1 . FIG. 1 is a block diagramshowing an example of the configuration of major parts of the electricalsystem in the radiographic imaging apparatus of the present embodiment.

As shown in FIG. 1 , the radiographic imaging apparatus 1 of the presentembodiment comprises the radiation detector 10, a control unit 100, adrive unit 102, a signal processing unit 104, an image memory 106, and apower source unit 108. At least one of the control unit 100, the driveunit 102, or the signal processing unit 104 of the present embodiment isan example of a circuit unit of the present disclosure. Hereinafter, thecontrol unit 100, the drive unit 102, and the signal processing unit 104are collectively referred to as the “circuit unit”.

The radiation detector 10 comprises the sensor substrate 12 and aconversion layer 14 (refer to FIG. 3 ) that converts radiation intolight. The sensor substrate 12 comprises a flexible base material 11,and a plurality of pixels 30 provided on a first surface 11A of the basematerial 11. In addition, in the following description, the plurality ofpixels 30 may be simply referred to as “pixels 30”.

As shown in FIG. 1 , each pixel 30 of the present embodiment comprises asensor unit 34 that generates and accumulates electric charges inresponse to the light converted by the conversion layer, and a switchingelement 32 that reads out the electric charges accumulated in the sensorunit 34. In the present embodiment, as an example, a thin filmtransistor (TFT) is used as the switching element 32. For that reason,in the following description, the switching element 32 is referred to asa “TFT 32”. In the present embodiment, a layer in which the pixels 30are formed on the first surface 11A of the base material 11 is providedas a layer that is formed with the sensor unit 34 and the TFT 32 and isplanarized.

The pixels 30 are two-dimensionally disposed in one direction (ascanning wiring direction corresponding to a transverse direction ofFIG. 1 , hereinafter referred to as a “row direction”), and a directionintersecting the row direction (a signal wiring direction correspondingto the longitudinal direction of FIG. 1 , hereinafter referred as a“column direction”) in a pixel region 35 of the sensor substrate 12.Although an array of the pixels 30 is shown in a simplified manner inFIG. 1 , for example, 1024×1024 pixels 30 are arranged in the rowdirection and the column direction.

Additionally, a plurality of scanning wiring lines 38, which areprovided for respective rows of the pixels 30 to control switchingstates (ON and OFF) of the TFT 32, and a plurality of signal wiringlines 36, which are provided for respective columns of the pixels 30 andfrom which electric charges accumulated in the sensor units 34 are read,are provided in a mutually intersecting manner in the radiation detector10. Each of the plurality of scanning wiring lines 38 is connected tothe drive unit 102 via a flexible cable 112A, and thereby, a drivesignal for driving the TFT 32 output from the drive unit 102 to controlthe switching state thereof flows through each of the plurality ofscanning wiring lines 38. Additionally, the plurality of signal wiringlines 36 are electrically connected to the signal processing unit 104via the flexible cable 112B, respectively, and thereby, electric chargesread from the respective pixels 30 are output to the signal processingunit 104 as electrical signals. The signal processing unit 104 generatesand outputs image data according to the input electrical signals. Inaddition, in the present embodiment, the term “connection” with respectto the flexible cable 112 means an electrical connection.

The control unit 100 to be described below is connected to the signalprocessing unit 104, and the image data output from the signalprocessing unit 104 is sequentially output to the control unit 100. Theimage memory 106 is connected to the control unit 100, and the imagedata sequentially output from the signal processing unit 104 issequentially stored in the image memory 106 under the control of thecontrol unit 100. The image memory 106 has a storage capacity capable ofstoring image data equivalent to a predetermined number of sheets, andwhenever radiographic images are captured, image data obtained by thecapturing is sequentially stored in the image memory 106.

The control unit 100 comprises a central processing unit (CPU) 100A, amemory 100B including a read only memory (ROM), a random access memory(RAM), and the like, and a nonvolatile storage unit 100C, such as aflash memory. An example of the control unit 100 is a microcomputer orthe like. The control unit 100 controls the overall operation of theradiographic imaging apparatus 1.

In addition, in the radiographic imaging apparatus 1 of the presentembodiment, the image memory 106, the control unit 100, and the like areformed in a control substrate 110.

Additionally, common wiring lines 39 are provided in a wiring directionof the signal wiring lines 36 at the sensor units 34 of the respectivepixels 30 in order to apply bias voltages to the respective pixels 30.Bias voltages are applied to the respective pixels 30 from a bias powersource by electrically connecting the common wiring lines 39 to the biaspower source (not shown) outside the sensor substrate 12.

The power source unit 108 supplies electrical power to various elementsand various circuits, such as the control unit 100, the drive unit 102,the signal processing unit 104, the image memory 106, and the powersource unit 108. In addition, in FIG. 1 , an illustration of wiringlines, which connect the power source unit 108 and various elements orvarious circuits together, is omitted in order to avoid complications.

Moreover, the radiation detector 10 will be described in detail. FIG. 2is an example of a plan view of the radiation detector 10 according tothe present embodiment as seen from the first surface 11A side of thebase material 11. Additionally, FIG. 3 is an example of across-sectional view taken along line A-A of the radiation detector 10in FIG. 2 .

The base material 11 is a resin sheet that has flexibility and includes,for example, a plastic such as a polyimide (PI). The thickness of thebase material 11 may be a thickness such that desired flexibility isobtained depending on the hardness of a material, the size of the sensorsubstrate 12, that is, the area of the first surface 11A or a secondsurface 11B, and the like. In a case where a rectangular base material11 is a single body, an example having flexibility indicates one inwhich the base material 11 hangs down (becomes lower than the height ofthe fixed side) 2 mm or more due to the gravity of the base material 11resulting from its own weight at a position 10 cm away from the fixedside with one side of the base material 11 fixed. As a specific examplein a case where the base material 11 is the resin sheet, the thicknessthereof may be 5 μm to 125 μm, and the thickness thereof may be morepreferably 20 μm to 50 μm.

In addition, the base material 11 has characteristics capable ofwithstanding the manufacture of the pixels 30 and has characteristicscapable of withstanding the manufacture of amorphous silicon TFT (a-SiTFT) in the present embodiment. As such a characteristic of the basematerial 11, it is preferable that the coefficient of thermal expansion(CTE) at 300° C. to 400° C. is about the same as that of amorphoussilicon (a-Si) wafer (for example, ±5 ppm/K), specifically, thecoefficient of thermal expansion is preferably 20 ppm/K or less.Additionally, as the thermal shrinkage rate of the base material 11, itis preferable that the thermal shrinkage rate at 400° C. is 0.5% or lesswith the thickness being 25 μm. Additionally, it is preferable that theelastic modulus of the base material 11 does not have a transition pointthat general PI has, in a temperature region of 300° C. to 400° C., andthe elastic modulus at 500° C. is 1 GPa or more.

Additionally, it is preferable that the base material 11 of the presentembodiment has a fine particle layer containing inorganic fine particleshaving an average particle diameter of 0.05 μm or more and 2.5 μm orless, which absorbs backscattered rays by itself in order to suppressbackscattered rays. In addition, as the inorganic fine particles, in thecase of the resinous base material 11, it is preferable to use aninorganic substance of which the atomic number is larger than the atomsconstituting the organic substance that is the base material 11 and is30 or less. Specific examples of such fine particles include SiO₂ thatis an oxide of Si having an atomic number of 14, MgO that is an oxide ofMg having an atomic number of 12, Al₂O₃ that is an oxide of Al having anatomic number of 13, TiO₂ that is an oxide of Ti having an atomic numberof 22, and the like. A specific example of the resin sheet having suchcharacteristics is XENOMAX (registered trademark).

In addition, the above thicknesses in the present embodiment weremeasured using a micrometer. The coefficient of thermal expansion wasmeasured according to JIS K7197:1991. In addition, the measurement wasperformed by cutting out test pieces from a main surface of the basematerial 11 while changing the angle by 15 degrees, measuring thecoefficient of thermal expansion of each of the cut-out test pieces, andsetting the highest value as the coefficient of thermal expansion of thebase material 11. The coefficient of thermal expansion is measured atintervals of 10° C. between −50° C. and 450° C. in a machine direction(MD) and a transverse direction (TD), and (ppm/° C.) is converted to(ppm/K). For the measurement of the coefficient of thermal expansion,the TMA4000S apparatus made by MAC Science Co., Ltd. is used, samplelength is 10 mm, sample width is 2 mm, initial load is 34.5 g/mm²,temperature rising rate is 5° C./min, and the atmosphere is in argon.

The base material 11 having desired flexibility is not limited to aresinous material such as the resin sheet. For example, the basematerial 11 may be a glass substrate or the like having a relativelysmall thickness. As a specific example of a case where the base material11 is the glass substrate, generally, in a size of about 43 cm on aside, the glass substrate has flexibility as long as the thickness is0.3 mm or less. Therefore, any desired glass substrate may be used aslong as the thickness is 0.3 mm or less.

As shown in FIGS. 2 and 3 , the plurality of pixels 30 are provided onthe first surface 11A of the base material 11. In the presentembodiment, a region on the first surface 11A of the base material 11where the pixels 30 are provided is the pixel region 35.

Additionally, the conversion layer 14 is provided on the first surface11A of the base material 11. The conversion layer 14 of the presentembodiment covers the pixel region 35. In the present embodiment, ascintillator including CsI (cesium iodide) is used as an example of theconversion layer 14. It is preferable that such a scintillator includes,for example, CsI:Tl (cesium iodide to which thallium is added) or CsI:Na(cesium iodide to which sodium is added) having an emission spectrum of400 nm to 700 nm at the time of X-ray irradiation. In addition, theemission peak wavelength in a visible light region of CsI:Tl is 565 nm.

In a case where the conversion layer 14 is formed by the vapor-phasedeposition method, as shown in FIG. 3 , the conversion layer 14 isformed with an inclination such that the thickness thereof graduallydecreases toward an outer edge thereof. In the following, a centralregion of the conversion layer 14 where the thickness in a case wheremanufacturing errors and measurement errors are neglected can beconsidered to be substantially constant is referred to as a central part14A. Additionally, an outer peripheral region of the conversion layer 14having a thickness of, for example, 90% or less of the average thicknessof the central part 14A of the conversion layer 14 is referred to as aperipheral edge part 14B. That is, the conversion layer 14 has aninclined surface that is inclined with respect to the sensor substrate12 at the peripheral edge part 14B. In addition, in the following, forconvenience of description, in a case where “upper” or “lower” arementioned on the sensor substrate 12, the conversion layer 14 is used asa reference, the side of the conversion layer 14 facing with the sensorsubstrate 12 is referred to as “lower”, and the opposite side isreferred to as “upper”. For example, the conversion layer 14 is providedon the sensor substrate 12, and the inclined surface of the peripheraledge part 14B of the conversion layer 14 is inclined in a state wherethe conversion layer 14 gradually expands from the upper side to thelower side.

Additionally, as shown in FIG. 3 , a pressure-sensitive adhesive layer60, a reflective layer 62, an adhesive layer 64, and a protective layer66 are provided on the conversion layer 14 of the present embodiment.

The pressure-sensitive adhesive layer 60 covers the entire surface ofthe conversion layer 14. The pressure-sensitive adhesive layer 60 has afunction of fixing the reflective layer 62 to the conversion layer 14.The pressure-sensitive adhesive layer 60 preferably has opticaltransmittance. As materials of the pressure-sensitive adhesive layer 60,for example, an acrylic pressure sensitive adhesive, a hot-melt pressuresensitive adhesive, and a silicone adhesive can be used. Examples of theacrylic pressure sensitive adhesive include urethane acrylate, acrylicresin acrylate, epoxy acrylate, and the like. Examples of the hot-meltpressure sensitive adhesive include thermoplastics, such asethylene-vinyl acetate copolymer resin (EVA), ethylene-acrylatecopolymer resin (EAA), ethylene-ethyl acrylate copolymer resin (EEA),and ethylene-methyl methacrylate copolymer (EMMA). The thickness of thepressure-sensitive adhesive layer 60 is preferably 2 μm or more and 7 μmor less. By setting the thickness of the pressure-sensitive adhesivelayer 60 to 2 μm or more, the effect of fixing the reflective layer 62on the conversion layer 14 can be sufficiently exhibited. Moreover, therisk of forming an air layer between the conversion layer 14 and thereflective layer 62 can be suppressed. When an air layer is formedbetween the conversion layer 14 and the reflective layer 62, there is aconcern that multiple reflections may be caused in which the lightemitted from the conversion layer 14 repeats reflections between the airlayer and the conversion layer 14 and between the air layer and thereflective layer 62. Additionally, by setting the thickness of thepressure-sensitive adhesive layer 60 to 7 μm or less, it is possible tosuppress a decrease in modulation transfer function (MTF) and detectivequantum efficiency (DQE).

The reflective layer 62 covers the entire surface of thepressure-sensitive adhesive layer 60. The reflective layer 62 has afunction of reflecting the light converted by the conversion layer 14.The material of the reflective layer 62 is preferably made of a resinmaterial containing a metal or a metal oxide. As the material of thereflective layer 62, for example, white PET (Polyethyleneterephthalate), TiO₂, Al₂O₃, foamed white PET, specular reflectivealuminum, and the like can be used. White PET is obtained by adding awhite pigment such as TiO₂ or barium sulfate to PET, and foamed whitePET is white PET having a porous surface. Additionally, as the materialof the reflective layer 62, a laminated film of a resin film and a metalfilm may be used. Examples of the laminated film of the resin film andthe metal film include an Alpet (registered trademark) sheet in whichaluminum is laminated by causing an aluminum foil to adhere to aninsulating sheet (film) such as polyethylene terephthalate. Thethickness of the reflective layer 62 is preferably 10 μm or more and 40μm or less. In this way, by comprising the reflective layer 62 on theconversion layer 14, the light converted by the conversion layer 14 canbe efficiently guided to the pixels 30 of the sensor substrate 12.

The adhesive layer 64 covers the entire surface of the reflective layer62. An end part of the adhesive layer 64 extends to the first surface11A of the base material 11. That is, the adhesive layer 64 adheres tothe base material 11 of the sensor substrate 12 at the end part thereof.The adhesive layer 64 has a function of fixing the reflective layer 62and the protective layer 66 to the conversion layer 14. As the materialof the adhesive layer 64, the same material as the material of thepressure-sensitive adhesive layer 60 can be used, but the adhesive forceof the adhesive layer 64 is preferably larger than the adhesive force ofthe pressure-sensitive adhesive layer 60.

The protective layer 66 is provided in a state where the protectivelayer covers the entire conversion layer 14 and the end part thereofcovers a part of the sensor substrate 12. The protective layer 66functions as a moistureproof film that prevents moisture from enteringthe conversion layer 14. As the material of the protective layer 66, forexample, organic films containing organic materials such as PET,polyphenylene sulfide (PPS), oriented polypropylene (OPP: biaxiallyoriented polypropylene film), polyethylene naphthalate (PEN), and PI,and Parylene (registered trademark) can be used. Additionally, as theprotective layer 66, a laminated film of a resin film and a metal filmmay be used. Examples of the laminated film of the resin film and themetal film include ALPET (registered trademark) sheets.

Meanwhile, as shown in FIGS. 2 and 3 , a plurality (16 in FIG. 2 ) ofthe terminals 113 are provided on an outer edge part of the firstsurface 11A of the base material 11. An anisotropic conductive film orthe like is used as the terminals 113. As shown in FIGS. 2 and 3 , theflexible cable 112 is electrically connected to each of the plurality ofterminals 113. Specifically, as shown in FIG. 2 , the flexible cable112A is thermocompression-bonded to each of the plurality of (eight inFIG. 2 ) terminals 113 provided on one side of the base material 11. Theflexible cable 112A is a so-called chip on film (COF), and a drivingintegrated circuit (IC) 210 is mounted on the flexible cable 112A. Thedriving IC 210 is connected to each of a plurality of signal linesincluded in the flexible cable 112A. In addition, in the presentembodiment, the flexible cable 112A and the flexible cable 112B to bedescribed below are simply referred to as “flexible cable 112” in a casewhere the cables are collectively referred to without distinction.

The other end of the flexible cable 112A opposite to the one endelectrically connected to the terminal 113 of the sensor substrate 12 iselectrically connected to the driving substrate 200. As an example, inthe present embodiment, the plurality of signal lines included in theflexible cable 112A are thermocompression-bonded to the drivingsubstrate 200 and thereby electrically connect to circuits and elements(not shown) mounted on the driving substrate 200. In addition, themethod of electrically connecting the driving substrate 200 and theflexible cable 112A is not limited to the present embodiment. Forexample, a configuration may be adopted in which the driving substrate200 and the flexible cable 112A are electrically connected by aconnector. Examples of such a connector include a zero insertion force(ZIF) structure connector and a Non-ZIF structure connector.

The driving substrate 200 of the present embodiment is a flexibleprinted circuit board (PCB), which is a so-called flexible substrate.Additionally, circuit components (not shown) mounted on the drivingsubstrate 200 are components mainly used for processing digital signals(hereinafter, referred to as “digital components”). Digital componentstend to have a relatively smaller area (size) than analog components tobe described below. Specific examples of the digital components includedigital buffers, bypass capacitors, pull-up/pull-down resistors, dampingresistors, electromagnetic compatibility (EMC) countermeasure chipcomponents, power source ICs, and the like. In addition, the drivingsubstrate 200 may not be necessarily a flexible substrate and may be anon-flexible rigid substrate or a rigid flexible substrate.

In the present embodiment, the drive unit 102 is realized by the drivingsubstrate 200 and the driving IC 210 mounted on the flexible cable 112A.In addition, the driving IC 210 includes, among various circuits andelements that realize the drive unit 102, circuits different from thedigital components mounted on the driving substrate 200.

Meanwhile, the flexible cable 112B is electrically connected to each ofthe plurality (eight in FIG. 2 ) of terminals 113 provided on a sideintersecting with one side of the base material 11 to which the flexiblecable 112A is electrically connected. Similar to the flexible cable112A, the flexible cable 112B is a so-called chip on film (COF), and asignal processing IC 310 is mounted on the flexible cable 112B. Thesignal processing IC 310 is connected to a plurality of signal lines(not shown) included in the flexible cable 112B.

The other end of the flexible cable 112B opposite to one endelectrically connected to the terminal 113 of the sensor substrate 12 iselectrically connected to the signal processing substrate 300. As anexample, in the present embodiment, the plurality of signal linesincluded in the flexible cable 112B are thermocompression-bonded to thesignal processing substrate 300 and thereby electrically connected tothe circuits and elements (not shown) mounted on the signal processingsubstrate 300. In addition, the method of electrically connecting thesignal processing substrate 300 and the flexible cable 112B is notlimited to the present embodiment. For example, a configuration may beadopted in which the signal processing substrate 300 and the flexiblecable 112B are electrically connected by a connector. Examples of such aconnector include a connector having a ZIF structure, a connector havinga Non-ZIF structure, and the like. Additionally, the method ofelectrically connecting the flexible cable 112A and the drivingsubstrate 200 and the method of electrically connecting the flexiblecable 112B and the signal processing substrate 300 may be the same ordifferent. For example, a configuration may be adopted in which theflexible cable 112A and the driving substrate 200 are electricallyconnected by thermocompression bonding, and the flexible cable 112B andthe signal processing substrate 300 are electrically connected by aconnector.

The signal processing substrate 300 of the present embodiment is aflexible PCB, which is a so-called flexible substrate, similarly to theabove-described driving substrate 200. Circuit components (not shown)mounted on the signal processing substrate 300 are components mainlyused for processing analog signals (hereinafter referred to as “analogcomponents”). Specific examples of the analog components include chargeamplifiers, analog-to-digital converters (ADCs), digital-to-analogconverters (DAC), and power source ICs. Additionally, the circuitcomponents of the present embodiment also include coils around a powersource, which has a relatively large component size, and large-capacitysmoothing capacitors. In addition, the signal processing substrate 300may not be necessarily a flexible substrate and may be a non-flexiblerigid substrate or a rigid flexible substrate.

In the present embodiment, the signal processing unit 104 is realized bythe signal processing substrate 300 and the signal processing IC 310mounted on the flexible cable 112B. In addition, the signal processingIC 310 includes, among various circuits and elements that realize thesignal processing unit 104, circuits different from the analogcomponents mounted on the signal processing substrate 300.

In addition, in FIG. 2 , a configuration in which a plurality of (two)the driving substrates 200 and a plurality of (two) the signalprocessing substrates 300 are provided has been described. However, thenumber of driving substrates 200 and the number of signal processingsubstrates 300 are not limited to those shown in FIG. 2 . For example, aconfiguration may be adopted in which at least one of the drivingsubstrate 200 or the signal processing substrate 300 may be a singlesubstrate.

Meanwhile, as shown in FIG. 3 , in the radiation detector 10 of thepresent embodiment, the flexible cable 112 is thermocompression-bondedto the terminal 113, and thereby the flexible cable 112 is electricallyconnected to the terminal 113. In addition, although FIG. 3 is a viewshowing an example of a structure relating to the electrical connectionbetween the flexible cable 112B and the radiation detector 10, astructure related to the electrical connection between the flexiblecable 112A and the radiation detector 10 of the present embodiment isalso the same as the configuration shown in FIG. 3 .

Additionally, as shown in FIG. 2 , an antistatic layer 48, anelectromagnetic shield layer 44, a pressure sensitive adhesive 42, and areinforcing substrate 40 are provided in order from the one closest tothe second surface 11B on the second surface 11B side of the basematerial 11 in the sensor substrate 12 of the radiation detector 10 ofthe present embodiment.

The antistatic layer 48 has a function of preventing the sensorsubstrate 12 from being charged and has a function of suppressing theinfluence of static electricity. As the antistatic layer 48, forexample, an antistatic paint “Colcoat” (product name: made by Colcoat),PET, polypropylene, and the like can be used.

The electromagnetic shield layer 44 has a function of suppressing theinfluence of electromagnetic wave noise from the outside. As thematerial of the electromagnetic shield layer 44, for example, alaminated film of a resin film such as Alpet (registered trademark) anda metal film can be used. In addition, although the details will bedescribed below, a foamed body layer 50 of the reinforcing substrate 40of the present embodiment contains a large number of cells, particularlyclosed cells 51A. Therefore, the electric resistance is relatively high.For that reason, it is preferable to include the electromagnetic shieldlayer 44 and the antistatic layer 48 similar to the radiation detector10 of the present embodiment.

Additionally, the reinforcing substrate 40 is provided on the surface ofthe electromagnetic shield layer 44 opposite to a surface facing theantistatic layer 48 by the pressure sensitive adhesive 42. Thereinforcing substrate 40 includes the foamed body layer 50, and has afunction of heat-insulating the pixel region 35 of the sensor substrate12 and a function of reinforcing the stiffness of the base material 11.

The foamed body layer 50 of the present embodiment uses a foamed bodymade of foamed plastic as a material. FIG. 4 shows cross-sectional viewsof an example of the reinforcing substrate 40 including the foamed bodylayer 50 of the present embodiment. The foamed body layer 50 shown inFIG. 4 is composed of the foam layer 50A. The foam layer 50A has aclosed cell structure based on the closed cells 51A.

Here, the cells in the foamed body will be described with reference toFIG. 5 . As shown in FIG. 5 , two types of cells, the closed cells 51Aand open cells 51B are present in the foamed body. The closed cells 51Aare cells that are present inside the foamed body and are isolated fromthe outside. On the other hand, the open cells 51B are cells that arepresent inside the foamed body but communicate with the outside.

Generally, the larger the number of closed cells 51A, the higher thestiffness of the foamed body and the higher the heat insulating property(lower the thermal conductivity). For that reason, the closed cell rateof the foamed body layer 50 of the present embodiment is preferably 85%or more.

In addition, the closed cell rate in the present embodiment was measuredby Measurement Method 1 (pressure change method) of JIS K7138: 2006, orMeasurement Method 2 (measurement of non-ventilated volume by a volumeexpansion method).

Additionally, the smaller the average cell diameter, which is theaverage of cell diameters r of the plurality of closed cells 51Acontained in the foamed body layer, the larger the bending breakingstrength and the more difficult it is to break. In a case where thefoamed body layer 50 is broken, there is a concern that the closed cellstructure is collapsed and the closed cells 51A become the open cells51B, and the bending stiffness and the heat insulating property arelowered. For that reason, it is preferable that the foamed body layer 50has a high bending breaking strength. For example, Reference Document 1describes that the bending breaking strength of the foamed body layer 50in which the average cell diameter of the closed cells 51A is 10 μm orless is 90% or more of the bending breaking strength of an unfoamed bodyof the same material.

-   [Reference Document 1] Minoru Shinbo, Michihide Ozawa, Kohei    Nishino, Akihiro Misawa, “Effect of cell refinement that contributes    to improvement of bending breaking strength of foamed body” General    Incorporated Association, The Japan Society Polymer Processing,    Molding Processing 23 (11), 685-690, 2011,

In this way, the average cell diameter of the closed cells 51A containedin the foamed body layer 50 of the present embodiment is preferably 10μm or less.

In addition, the average cell diameter in the present embodiment wasmeasured by a measuring method based on JIS K6402 or a measuring methodusing the following scanning electron microscope (SEM). In the scanningelectron microscope (SEM) measuring method, a cross section of thefoamed body layer 50 was observed at a magnification of 50 times byusing the scanning electron microscope (SEM), and the cell diameter wasmeasured using measuring software so that the longitudinal direction andthe width direction of cells within a range of 1 mm×1 mm of an obtainedimage were orthogonal to each other, the average cell diameter wasmeasured by calculation.

In addition, the foamed body layer 50 is not limited to theconfiguration shown in FIG. 4 , and as in the foamed body layer 50 shownin FIGS. 6A and 6B, a configuration having a multilayer structure inwhich a foam layer 50A and a non-foam layer 50B (50B₁ and 50B₂) arelaminated may be adopted. The foamed body layer 50 shown in FIG. 6A is aconfiguration example having a multilayer structure in which the foamlayer 50A and the non-foam layer 50B are laminated one by one in alamination direction in which the sensor substrate 12 and thereinforcing substrate 40 in the radiation detector 10 are laminated.Additionally, the foamed body layer 50 shown in FIG. 6B is aconfiguration example having a sandwich structure in which the foamlayer 50A is sandwiched between two non-foam layers 50B₁ and 50B₂(generically, simply referred to as “non-foam layer 50B”) in thelamination direction in which the sensor substrate 12 and thereinforcing substrate 40 in the radiation detector 10 are laminated. Inaddition, in the case of the sandwich structure in which the foam layer50A is sandwiched between the non-foam layers 50B as in the foamed bodylayer 50 shown in FIG. 6B, the closed cell rate of the foamed body layer50 is approximately 100%.

As in the foamed body layer 50 shown in FIGS. 6A and 6B, the bendingstiffness of the foamed body layer 50 can be increased by including thenon-foam layer 50B.

As the material of such a foamed body layer 50, foamed plastic or foamedmetal can be applied, and for example, at least one of foamed styrene,foamed PET, foamed polycarbonate, acrylic foamed body, polyethylenefoamed body, polyolefin foamed body, phenol resin foamed body, a foamedmetal such as aluminum, or the like can be mentioned. In addition, in acase where the foamed body layer 50 includes the foam layer 50A and thenon-foam layer 50B, it is preferable that the main component of the foamlayer 50A and the main component of the non-foam layer 50B are the same.

Additionally, the reinforcing substrate 40 of the present embodiment ishigher in bending stiffness than the base material 11, and thedimensional change (deformation) thereof with respect to a force appliedin a direction perpendicular to the surface facing the conversion layer14 is smaller than the dimensional change thereof with respect to aforce applied in the direction perpendicular to the second surface 11Bof the base material 11.

Specifically, the bending stiffness of the reinforcing substrate 40 ispreferably 100 times or more the bending stiffness of the base material11. Additionally, the thickness of the reinforcing substrate 40 of thepresent embodiment is larger than the thickness of the base material 11.For example, in a case where XENOMAX (registered trademark) is used asthe base material 11, the thickness of the reinforcing substrate 40 ispreferably about 0.1 mm to 1 mm.

Specifically, a material having a bending elastic modulus of 150 MPa ormore and 2,500 MPa or less is preferably used for the reinforcingsubstrate 40 of the present embodiment. From the viewpoint ofsuppressing the deflection of the base material 11, the reinforcingsubstrate 40 preferably has a higher bending stiffness than the basematerial 11. In addition, in a case where the bending elastic modulusbecomes low, the bending stiffness also becomes low. In order to obtaina desired bending stiffness, the thickness of the reinforcing substrate40 should be made large, and the thickness of the entire radiationdetector 10 increases. Considering the material of the above-describedreinforcing substrate 40, the thickness of the reinforcing substrate 40tends to be relatively large in a case where a bending stiffnessexceeding 9 MPacm⁴ is to be obtained. For that reason, in view ofobtaining appropriate stiffness and considering the thickness of theentire radiation detector 10, the material used for the reinforcingsubstrate 40 preferably has a bending elastic modulus of 150 MPa or moreand 2,500 MPa or less. Additionally, the bending stiffness of thereinforcing substrate 40 is preferably 540 Pacm⁴ or more and 9 MPacm⁴ orless.

Additionally, the coefficient of thermal expansion of the reinforcingsubstrate 40 of the present embodiment is preferably closer to thecoefficient of thermal expansion of the material of the conversion layer14, and the ratio of the coefficient of thermal expansion of thereinforcing substrate 40 to the coefficient of thermal expansion of theconversion layer 14 (the coefficient of thermal expansion of thereinforcing substrate 40/the coefficient of thermal expansion of theconversion layer 14) is more preferably 0.5 or more and 2 or less. Forexample, in a case where the conversion layer 14 has CsI:Tl as amaterial, the coefficient of thermal expansion is 50 ppm/K. Therefore,in a case where the conversion layer 14 uses CsI:Tl as a material, thecoefficient of thermal expansion of the reinforcing substrate 40 ispreferably 25 ppm/K or more and 100 ppm/K or less, and more preferably30 ppm/K or more and 80 ppm/K or less.

From the viewpoint of elasticity, the reinforcing substrate 40preferably contains a material having a yield point. In addition, in thepresent embodiment, the “yield point” means a phenomenon in which thestress rapidly decreases once in a case where the material is pulled,means that the strain is increased without increasing the stress on acurve representing a relationship between the stress and the strain, andindicates the peak of a stress-strain curve in a case where a tensilestrength test is performed on the material. Resins having the yieldpoint generally include resins that are hard and strongly sticky, andresins that are soft and strongly sticky and have medium strength.

From the viewpoint of the above-described heat insulating property andstiffness, it is preferable that the material of the foamed body layer50 of the present embodiment contains at least one of foamed styrene,foamed PET, or foamed polycarbonate as a main component. Specificexamples include MCPET (registered trademark) and MCPOLYCA (registeredtrademark). For example, in the case of MCPET (registered trademark),the bending elastic modulus at a thickness of 0.42 mm is 800 MPa, andthe bending stiffness is 212,000 Pacm⁴.

MCPET (registered trademark) and MCPOLYCA (registered trademark) have asandwich structure in which a foam layer corresponding to the foam layer50A of the present embodiment is sandwiched between unfoamed layerscorresponding to the non-foam layer 50B of the present embodiment. Inaddition, the foamed body layer 50 shown in FIG. 4 or the foamed bodylayer 50 shown in FIG. 6A can be applied by polishing both sides or oneside of MCPET (registered trademark) and MCPOLYCA (registered trademark)to remove the foam layer.

Moreover, the radiographic imaging apparatus 1 will be described indetail. FIG. 7A is an example of a cross-sectional view of aradiographic imaging apparatus 1 in a case where the radiation detector10 of the present embodiment is applied to an irradiation side sampling(ISS) type in which radiation is emitted from the second surface 11Bside of the base material 11. Additionally, FIG. 7B is an example of across-sectional view of the radiographic imaging apparatus 1 in a casewhere the radiation detector 10 of the present embodiment is applied tothe penetration side sampling (PSS) type in which radiation isirradiated from the conversion layer 14 side.

The radiographic imaging apparatus 1 formed of the above radiationdetector 10 is used while being housed in a housing 120, as shown inFIGS. 7A and 7B. As shown in FIGS. 7A and 7B, the radiation detector 10,the power source unit 108, and the circuit unit such as the signalprocessing substrate 300 are provided side by side in an incidencedirection of radiation within the housing 120. The radiation detector 10of FIG. 7A is disposed in a state where the second surface 11B of thebase material 11 faces a top plate on an irradiation surface 120A sideof the housing 120 that is irradiated with the radiation transmittedthrough a subject. More specifically, the reinforcing substrate 40 isdisposed so as to face the top plate on the irradiation surface 120Aside of the housing 120. Additionally, the radiation detector 10 of FIG.7B is disposed in a state where the first surface 11A side of the basematerial 11 faces the top plate on the irradiation surface 120A side ofthe housing 120. More specifically, an upper surface of the conversionlayer 14 is disposed so as to face the top plate on the irradiationsurface 120A side of the housing 120.

Additionally, a middle plate 116 is further provided on a side fromwhich the radiation transmitted through the radiation detector 10 isemitted, within the housing 120 as shown in FIGS. 7A and 7B. The middleplate 116 is, for example, an aluminum or copper sheet. The copper sheetdoes not easily generate secondary radiation due to incident radiation,and therefore, has a function of preventing scattering to the rear side,that is, the conversion layer 14 side. In addition, it is preferablethat the middle plate 116 covers at least an entire surface of theconversion layer 14 from which radiation is emitted, and covers theentire conversion layer 14. Additionally, a circuit unit such as asignal processing substrate 300 is fixed to the middle plate 116.

The housing 120 is preferably lightweight, has a low absorbance ofradiation, particularly X-rays, and has a high stiffness, and is morepreferably made of a material having a sufficiently high elasticmodulus. As the material of the housing 120, it is preferable to use amaterial having a bending modulus of elasticity of 10,000 MPa or more.As the material of the housing 120, carbon or carbon fiber reinforcedplastics (CFRP) having a bending modulus of elasticity of about 20,000MPa to 60,000 MPa can be suitably used.

In the capturing of a radiographic image by the radiographic imagingapparatus 1, a load from a subject is applied to the irradiation surface120A of the housing 120. In a case where the stiffness of the housing120 is insufficient, there are concerns that problems may occur suchthat the sensor substrate 12 is deflected due to the load from thesubject and the pixels 30 are damaged. By housing the radiation detector10 inside the housing 120 made of a material having a bending modulus ofelasticity of 10,000 MPa or more, it is possible to suppress thedeflection of the sensor substrate 12 due to the load from the subject.

In addition, the housing 120 may be formed of different materials forthe irradiation surface 120A of the housing 120 and other portions. Forexample, a portion corresponding to the irradiation surface 120A may beformed of a material having a low radiation absorbance and highstiffness and having a sufficiently high elastic modulus, and the otherportions may be formed of a material different from the portioncorresponding to the irradiation surface 120A, for example, a materialhaving a lower elastic modulus than the portion of the irradiationsurface 120A.

A method of manufacturing the radiographic imaging apparatus 1 of thepresent embodiment will be described with reference to FIGS. 8A to 8F.In addition, the method of manufacturing the radiographic imagingapparatus 1 of the present embodiment includes a method of manufacturingthe radiation detector 10 of the present embodiment.

As shown in FIG. 8A, the base material 11 is provided on a support body400, such as a glass substrate having a thickness larger than that ofthe base material 11, via a peeling layer 402, for example in order toform the sensor substrate 12. For example, in a case where the basematerial 11 is formed by a lamination method, a sheet to be the basematerial 11 is bonded onto the support body 400. The second surface 11Bof the base material 11 is in contact with the peeling layer 402. Inaddition, the method of forming the base material 11 is not limited tothe present embodiment. For example, a configuration may be adopted inwhich the base material 11 is formed by a coating method.

Moreover, the pixels 30 and terminal 113 are formed on the first surface11A of the base material 11. The pixel 30 is formed via an undercoatlayer (not shown) formed of SiN or the like in the pixel region 35 ofthe first surface 11A. Additionally, a plurality of the terminals 113are formed along each of two sides of the base material 11.

Additionally, as shown in FIG. 8B, the conversion layer 14 is formed ona layer on which the pixels 30 are formed (hereinafter, simply referredto as “pixels 30”). In the present embodiment, the conversion layer 14of CsI is directly formed as a columnar crystal on the sensor substrate12 by vapor-phase deposition methods, such as a vacuum vapor depositionmethod, a sputtering method, and a chemical vapor deposition (CVD)method. In this case, the side of the conversion layer 14 in contactwith the pixels 30 is a growth-direction base point side of the columnarcrystal.

In addition, in a case where a CsI scintillator is used as theconversion layer 14, the conversion layer 14 can be formed on the sensorsubstrate 12 by a method different from the method of the presentembodiment. For example, the conversion layer 14 may be formed on thesensor substrate 12 by preparing one in which CsI is vapor-deposited onan aluminum or carbon substrate or the like by a vapor-phase depositionmethod and bonding a side of the CsI, which is not in contact with thesubstrate, and the pixels 30 of the sensor substrate 12 to each otherwith a pressure sensitive adhesive sheet or the like. In this case, itis preferable that one in which the entire conversion layer 14 alsoincluding a substrate of aluminum or the like is covered with aprotective layer is bonded to the pixels 30 of the sensor substrate 12.In addition, in this case, the side of the pixels 30 in contact with theconversion layer 14 is a distal end side in the growth direction of thecolumnar crystal.

Additionally, unlike the radiation detector 10 of the presentembodiment, GOS (Gd₂O₂S:Tb)) or the like may be used as the conversionlayer 14 instead of CsI. In this case, for example, the conversion layer14 can be formed on the sensor substrate 12 by preparing one in which asheet having GOS dispersed in a binder such as resin is bonded to asupport body formed of white PET or the like with a pressure-sensitiveadhesive layer or the like, and bonding a side of the GOS on which thesupport body is not bonded, and the pixel 30 of the sensor substrate 12to each other with the pressure sensitive adhesive sheet or the like. Inaddition, the conversion efficiency from radiation to visible light ishigher in a case where CsI is used for the conversion layer 14 than in acase where GOS is used.

Moreover, the reflective layer 62 is provided on the conversion layer 14formed on the sensor substrate 12 via the pressure-sensitive adhesivelayer 60. Moreover, the protective layer 66 is provided via the adhesivelayer 64.

Next, as shown in FIG. 8C, the flexible cable 112 is electricallyconnected to the sensor substrate 12. Specifically, the flexible cable112 on which the driving IC 210 or the signal processing IC 310 ismounted is thermocompression-bonded to the terminal 113 to electricallyconnect the terminal 113 and the flexible cable 112. Accordingly, theflexible cable 112 is electrically connected to the sensor substrate 12.

After that, as shown in FIG. 8D, the sensor substrate 12 provided withthe conversion layer 14 is peeled from the support body 400.Hereinafter, this step is referred to as a peeling step. In the case ofmechanical peeling, in an example shown in FIG. 8D, the side of the basematerial 11 of the sensor substrate 12 facing the side to which theflexible cable 112B is electrically connected is set as the startingpoint of the peeling. Also, the sensor substrate 12 is peeled from thesupport body 400 by gradually pulling off the support body 400 in thedirection of an arrow D shown in FIG. 8D from the side to be thestarting point toward the side to which the flexible cable 112 iselectrically connected.

In addition, it is preferable that the side to be the peeling startingpoint is a side that intersects the longest side in a case where thesensor substrate 12 is seen in a plan view. In other words, the side ina deflection direction Y in which the deflection is caused by thepeeling is preferably the longest side. As an example, in the presentembodiment, the peeling starting point is the side facing the side towhich the flexible cable 112B is electrically connected.

Next, as shown in FIG. 8D, the antistatic layer 48, the electromagneticshield layer 44, and the reinforcing substrate 40 are sequentiallyprovided on the second surface 11B of the base material 11. First, theantistatic layer 48 and the electromagnetic shield layer 44 are formedon the second surface 11B of the base material 11 by coating or thelike. Moreover, the reinforcing substrate 40 provided with the pressuresensitive adhesive 42 is bonded to the surface of the electromagneticshield layer 44 opposite to the antistatic layer 48 side.

Moreover, by housing the radiation detector 10, the circuit unit, andthe like in the housing 120, the radiographic imaging apparatus 1 shownin FIG. 7A or FIG. 7B is manufactured. Specifically, by housing theradiation detector 10 in the housing 120 in a state where thereinforcing substrate 40 faces the irradiation surface 120A, theradiographic imaging apparatus 1 shown in FIG. 7A is manufactured.Additionally, by housing the radiation detector 10 in the housing 120 ina state where the conversion layer 14 faces the irradiation surface120A, the radiographic imaging apparatus 1 shown in FIG. 7B ismanufactured.

In addition, in the above description, a configuration in which thereinforcing substrate 40 is provided on the second surface 11B side ofthe base material 11 of the sensor substrate 12 has been described, butas shown in FIG. 9A, a configuration may be adopted in which thereinforcing substrate 40 is provided on the first surface 11A side ofthe base material 11. FIG. 9A shows an example of a cross-sectional viewof the radiation detector 10 of the present embodiment, whichcorresponds to the cross-sectional view taken along line A-A of theradiation detector 10 shown in FIG. 3 . Specifically, as shown in FIG.9A, the radiation detector 10 may have a configuration in which thereinforcing substrate 40 is provided on the conversion layer 14 of thereinforcing substrate 40, more specifically, on the protective layer 66via the pressure sensitive adhesive 42.

Additionally, in a case where the reinforcing substrate 40 is providedon the conversion layer 14, for example, as shown in FIG. 9B, aconfiguration may be adopted in which the reinforcing substrate 40 islarger than the base material 11. In addition, the specific size of thereinforcing substrate 40 can be determined depending on the size of theinside of the housing 120 that houses the radiation detector 10, and thelike. In the radiation detector 10 shown in FIG. 9B, the end part of thereinforcing substrate 40 is located outside an end part of the basematerial 11, that is, the sensor substrate 12.

In this way, by making the size of the reinforcing substrate 40 largerthan the size of the base material 11, for example, for example, in acase where an impact is applied to the housing 120 and a side surface (asurface intersecting the irradiation surface 120A) of the housing 120 isrecessed such that the radiographic imaging apparatus 1 is dropped, thereinforcing substrate 40 interferes with the side surface of the housing120. On the other hand, since the sensor substrate 12 is smaller thanthe reinforcing substrate 40, the sensor substrate 12 is less likely tointerfere with the side surface of the housing 120. Therefore, accordingto the radiation detector 10 shown in FIG. 9B, it is possible tosuppress the influence of the impact applied to the radiographic imagingapparatus 1 on the sensor substrate 12.

In addition, from the viewpoint of suppressing the influence of theimpact of the reinforcing substrate 40 applied to the radiographicimaging apparatus 1 on the sensor substrate 12, as shown in FIG. 9B, atleast a part of the end part of the reinforcing substrate 40 mayprotrude further outward than the end part of the base material 11. Forexample, even in a case where the size of the reinforcing substrate 40is smaller than the size of the base material 11, the end part of thereinforcing substrate 40 that protrudes further outward than the endpart of the base material 11 interferes with the side surface of thehousing 120. Therefore, the influence of the impact on the sensorsubstrate 12 can be suppressed.

Additionally, for example, as shown in FIGS. 9C and 9D, a configurationmay be adopted in which the reinforcing substrate 40 is smaller than thebase material 11. In the example shown in FIG. 9C, the reinforcingsubstrate 40 is not provided at the position facing the terminal 113.That is, the area of the reinforcing substrate 40 in the radiationdetector 10 is smaller than a value obtained by subtracting the area ofa region where the terminal 113 is provided from the area of the basematerial 11. On the other hand, in an example shown in FIG. 9D, the endpart of the reinforcing substrate 40 is located at the peripheral edgepart 14B of the conversion layer 14, and the conversion layer 14 isprovided in a region narrower than a region where the reinforcingsubstrate 40 covers the entire first surface 11A of the base material11.

Removing the flexible cable 112 or a component electrically connected tothe base material 11 (sensor substrate 12) and newly reconnecting thecomponent due to a defect or a positional deviation is referred to asrework. In this way, by making the size of the reinforcing substrate 40smaller than the size of the base material 11, the rework can beperformed without being disturbed by the end part of the reinforcingsubstrate 40. Therefore, the rework of the flexible cable 112 can befacilitated.

Additionally, as shown in FIG. 10 , in the radiation detector 10, aconfiguration may be adopted in which a reinforcing substrate 40 ₁ isprovided on the second surface 11B side of the base material 11 of thesensor substrate 12 via a pressure sensitive adhesive 42 ₁, and areinforcing substrate 40 ₂ is provided on the conversion layer 14 via apressure sensitive adhesive 42 ₂.

In addition, the step of providing the reinforcing substrate 40 or thereinforcing substrate 40 ₂ on the conversion layer 14 may be performedafter the peeling step (refer to FIG. 8D) but is preferably performedbefore the peeling step. In a case where the sensor substrate 12provided with the conversion layer 14 is peeled from the support body400, the base material 11 is deflected. In a case where the basematerial 11 is deflected, there is a concern that the conversion layer14, particularly the end part of the conversion layer 14, may be peeledfrom the base material 11. In contrast, in a case where the sensorsubstrate 12 having the reinforcing substrate 40 or the reinforcingsubstrate 40 ₂ provided on the conversion layer 14 is peeled from thesupport body 400, it is possible to suppress the peeling of theconversion layer 14 from the base material 11, which is caused by thedeflection of the base material 11 in order to reinforce the bendingstiffness of the base material 11.

In addition, the configuration and manufacturing method of theradiographic imaging apparatus 1 and the radiation detector 10 are notlimited to the above-described form. For example, the configurationsshown in the following Modification Examples 1 to 4 may be used. Inaddition, configurations may be adopted in which the above-describedform and respective Modification Examples 1 to 4 are combinedappropriately, and the disclosure is not limited to ModificationExamples 1 to 4.

Modification Example 1

In the present modification example, a modification example of thereinforcing substrate 40 will be described with reference to FIGS. 11Ato 11E. In the above description, a configuration in which thereinforcing substrate 40 includes only the foamed body layer 50 has beendescribed, but the reinforcing substrate 40 may have a configurationincluding other than the foamed body layer 50.

FIG. 11A shows an example of a cross-sectional view of the reinforcingsubstrate 40 in a case where the reinforcing substrate 40 includes thefoamed body layer 50 and a rigid plate 52.

The rigid plate 52 has a higher bending stiffness than the base material11. In addition, a relationship between the bending stiffness of therigid plate 52 and the bending stiffness of the reinforcing substrate 40is not limited. That is, the bending stiffness of the rigid plate 52 maybe about the same as that of the reinforcing substrate 40, may be lowerthan that of the reinforcing substrate 40, or may be higher than that ofthe reinforcing substrate 40. In addition, in a case where the foamedbody layer 50 and the rigid plate 52 have the same thickness, it ispreferable that the bending stiffness of the rigid plate 52 is higher.

Examples of the material of such a rigid plate 52 include reinforcedfiber resin and the like, and it is preferable that CFRP is contained asa main component. In addition, in the present embodiment, CRFP is usedas the material of the rigid plate 52.

The thickness of the rigid plate 52 is smaller than the thickness of thefoamed body layer 50. In other words, the thickness of the foamed bodylayer 50 is larger than the thickness of the rigid plate 52. The foamedbody layer 50 is lighter than the rigid plate 52 and the bendingstiffness depends on the cube of the thickness. Therefore, by increasingthe thickness of the foamed body layer 50, the weight can be reducedwhile maintaining the bending stiffness of the reinforcing substrate 40.

The reinforcing substrate 40 shown in FIG. 11A is a laminated body inwhich a rigid plate 52 in which two layers of a first rigid plate 52Aand a second rigid plate 52B are laminated, and the foamed body layer 50are laminated. The first rigid plate 52A is a CFRP rigid plate in whichcarbon fibers are stretched in a first direction. The second rigid plate52B is a CFRP rigid plate in which carbon fibers are stretched in adirection intersecting the first direction. In this way, by using twolayers of CFRP having different stretching directions of the carbonfibers in combination, the bending stiffness can be further improved.

In addition, in the case of the reinforcing substrate 40 shown in FIG.11A, either the foamed body layer 50 or the rigid plate 52 may be on thesensor substrate 12 side. In addition, in a case where the foamed bodylayer 50 is on the sensor substrate 12 side, the reinforcing substrate40 can be used as the above-described middle plate 116 (refer to FIGS.7A and 7B).

On the other hand, the reinforcing substrate 40 shown in FIG. 11B is alaminated body having a sandwich structure in which the foamed bodylayer 50 is sandwiched between a rigid plate 52 ₁ in which two layers ofthe first rigid plate 52A and the second rigid plate 52B are laminated,and a rigid plate 52 ₂ in which two layers of the first rigid plate 52Aand the second rigid plate 52B are laminated. In addition, in thefollowing, in a case where the reinforcing substrate 40 includes aplurality of rigid plates 52, and in a case where the individual rigidplates are generically referred to without being distinguished from eachother, reference numerals representing the individual rigid plates areomitted and the individual rigid plates are simply referred to as “rigidplate 52”.

Additionally, the reinforcing substrate 40 shown in FIG. 11C is alaminated body having a sandwich structure in which the foamed bodylayer 50 ₁ is sandwiched between the rigid plate 52 ₁ in which twolayers of the first rigid plate 52A and the second rigid plate 52B arelaminated, and the rigid plate 52 ₂ in which two layers of the firstrigid plate 52A and the second rigid plate 52B are laminated, and afoamed body layer 50 ₂ is sandwiched between the rigid plate 52 ₂ and arigid plate 52 ₃ in which two layers of the first rigid plate 52A andthe second rigid plate 52B are laminated.

Additionally, the reinforcing substrate 40 shown in FIG. 11D is alaminated body having a sandwich structure in which the foamed bodylayer 50 ₁ is sandwiched between the rigid plate 52 ₁, which is onelayer of the first rigid plate 52A, and the rigid plate 52 ₂, which isone layer of the second rigid plate 52B, the foamed body layer 50 ₂ issandwiched between the rigid plate 52 ₂, and the rigid plate 52 ₃, whichis one layer of the first rigid plate 52A, and a foamed body layer 50 ₃is sandwiched between the rigid plate 52 ₃ and a rigid plate 52 ₄, whichis one layer of the second rigid plate 52B.

Each of the rigid plates 52 of the reinforcing substrate 40 shown inFIG. 11D is the first rigid plate 52A or the second rigid plate 52B, andis a one-layer CFRP, but can be regarded as a laminated body in whichthe first rigid plate 52A and the second rigid plate 52B are alternatelylaminated, as a whole of the reinforcing substrate 40. For that reason,similarly to the rigid plates 52 of the reinforcing substrate 40 shownin FIGS. 11A to 11C, two layers of CFRP having different stretchingdirections of the carbon fibers are used in combination, and the bendingstiffness can be further improved.

In addition, as shown in FIG. 11E, the rigid plate 52 may have aso-called punching structure having a plurality of holes 53. By formingthe rigid plate 52 into the punching structure, the weight of the rigidplate 52 can be reduced. In addition, in this case, the number,position, shape, and the like of the holes 53 of the rigid plate 52 arenot limited to the example shown in FIG. 11E. The number, position,shape, and the like of the holes 53 of the rigid plate 52 can bedetermined depending on characteristics such as the desired bendingstiffness of the rigid plate 52. For example, the shape of the hole 53is not limited to a circular shape, and may be a quadrangular shape, ahexagonal shape, or the like. Additionally, the first rigid plate 52Aand the second rigid plate 52B having different positions of the holes53 may be used in combination.

In this way, in the present modification example, the reinforcingsubstrate 40 of the radiation detector 10 includes the foamed body layer50 and the rigid plate 52. For that reason, according to the radiationdetector 10 of the present modification example, the bending stiffnessof the reinforcing substrate 40 can be further increased. Additionally,the weight can be reduced as compared to a case where only the rigidplate 52 is used as a reinforcing substrate plate of the radiationdetector 10.

Modification Example 2

In the present modification example, a configuration in which thereinforcing substrate 40 provided on the first surface 11A side of thebase material 11, specifically, on the conversion layer 14 in theradiation detector 10 is supported by the support member 72 will bedescribed with reference to FIGS. 12A and 12B. Each of FIGS. 12A and 12Bshows an example of a cross-sectional view of a radiation detector 10 ofthe present modification example, which corresponds to thecross-sectional view taken along the line A-A of the radiation detector10 illustrated in FIG. 3 .

In the radiation detector 10 shown in FIG. 12A, the end part of thereinforcing substrate 40 is supported by the support member 72. That is,one end of the support member 72 is connected to the flexible cable 112or the first surface 11A of the base material 11, and the other end ofthe support member 72 is connected to the end part of the reinforcingsubstrate 40 by the pressure sensitive adhesive 92. In addition, thesupport member 72 may be provided on the entire outer edge part of thebase material 11 or may be provided on a portion of the outer edge part.In this way, by supporting the end part of the reinforcing substrate 40that extends while forming the space between the reinforcing substrate40 and the base material 11 with the support member 72, the peeling ofthe conversion layer 14 from the sensor substrate 12 can be suppressed.Additionally, by providing the support member 72 on the flexible cable112 connected to the terminal 113, it is possible to suppress thepeeling of the flexible cable 112 from the terminal 113.

On the other hand, in the radiation detector 10 shown in FIG. 12B, aposition inside the end part of the reinforcing substrate 40 issupported by the support member 72. In the example shown in FIG. 12B,the position where the support member 72 is provided is only outside theregion where the flexible cable 112 and the terminal 113 are provided.In the example shown in FIG. 12B, one end of the support member 72 isconnected to the first surface 11A of the base material 11, and theother end of the support member 72 is connected to the end part of thereinforcing substrate 40 by the pressure sensitive adhesive 42. In thisway, by not providing the support member 72 on the flexible cable 112and the terminal 113, the rework of the flexible cable 112 can befacilitated.

In this way, according to the radiation detector 10 of the presentmodification example, by supporting the reinforcing substrate 40 withthe support member 72, the stiffness reinforcing effect of thereinforcing substrate 40 can be obtained up to the vicinity of the endpart of the base material 11, and the effect of suppressing thedeflection of the base material 11 can be exerted. For that reason,according to the radiation detector 10 of the present modificationexample, the peeling of the conversion layer 14 from the sensorsubstrate 12 can be suppressed.

Modification Example 3

In the present modification example, a configuration in which theperiphery of the conversion layer 14 in the radiation detector 10 issealed will be described with reference to FIG. 13 . FIG. 13 shows anexample of a cross-sectional view of a radiation detector 10 of thepresent modification example, which corresponds to the cross-sectionalview taken along the line A-A of the radiation detector 10 shown in FIG.3 .

As shown in FIG. 13 , a configuration may be adopted in which theperipheral edge part 14B of the conversion layer 14 is sealed by asealing member 70. In the example shown in FIG. 13 , the sealing member70 is provided in a space created by the base material 11, theconversion layer 14, and the reinforcing substrate 40 as describedabove. Specifically, a sealing member 70 is provided in a space formedbetween the conversion layer 14 (protective layer 66) and thereinforcing substrate 40 in the region corresponding to the peripheraledge part 14B of the conversion layer 14 and the region further outsidethereof. The material of the sealing member 70 is not particularlylimited, and for example, resin can be used.

The method of providing the sealing member 70 is not particularlylimited. For example, the reinforcing substrate 40 may be provided onthe conversion layer 14 covered with a pressure-sensitive adhesive layer60, the reflective layer 62, the adhesive layer 64, and the protectivelayer 66 by the pressure sensitive adhesive 42, and then, the sealingmember 70 having fluidity may be injected into the space formed betweenthe conversion layer 14 (protective layer 66) and the reinforcingsubstrate 40 to cure the reinforcing substrate 40. Additionally, forexample, after the conversion layer 14, the pressure-sensitive adhesivelayer 60, the reflective layer 62, the adhesive layer 64, and theprotective layer 66 are sequentially formed on the base material 11, thesealing member 70 may be formed, and the reinforcing substrate 60 may beprovided by the pressure sensitive adhesive 42 in a state where theconversion layer 14 and the sealing member 70 covered with thepressure-sensitive adhesive layer 40, the reflective layer 62, theadhesive layer 64, and the protective layer 66.

Additionally, the region where the sealing member 70 is provided is notlimited to the configuration shown in FIG. 13 . For example, the sealingmember 70 may be provided on the entire first surface 11A of the basematerial 11, and the terminal 113 to which the flexible cable 112 iselectrically connected may be sealed together with the flexible cable112.

In this way, by filling the space formed between the conversion layer 14and the reinforcing substrate 40 with the sealing member 70 and sealingthe conversion layer 14, the peeling of the reinforcing substrate 40from the conversion layer 14 can be suppressed. Moreover, since theconversion layer 14 has a structure in which the conversion layer 14 isfixed to the sensor substrate 12 by both the reinforcing substrate 40and the sealing member 70, the stiffness of the base material 11 isfurther reinforced.

In addition, in a case where the present modification example and theabove Modification Example 2 are combined with each other, in otherwords, in a case where the radiation detector 10 comprises the sealingmember 70 and the support member 72, a configuration may be adopted inwhich a part or the whole of the space surrounded by the support member72, the reinforcing substrate 40, the conversion layer 14, and the basematerial 11 may be filled with the sealing member 70 and may be sealedby the sealing member 70.

Modification Example 4

In the present modification example, a modification example of theradiographic imaging apparatus 1 will be described with reference toFIGS. 14A to 14E. Each of FIGS. 14A to 14E is an example ofcross-sectional views of a radiographic imaging apparatus 1 of thepresent modification example.

FIG. 14A shows an example of the ISS type radiographic imaging apparatus1 in which the radiation detector 10 is in contact with the inner wallsurface of the top plate on the irradiation surface 120A side of thehousing 120. In the example shown in FIG. 14A, the reinforcing substrate40 is in contact with the inner wall surface of the top plate on theirradiation surface 120A side of the housing 120. In addition, in thecase of the PSS type radiographic imaging apparatus 1, a configurationis provided the conversion layer 14 or the reinforcing substrate 40provided on the conversion layer 14 is in contact with the inner wallsurface of the top plate on the irradiation surface 120A side of thehousing 120

In this case, the radiation detector 10 and the inner wall surface ofthe housing 120 may be bonded to each other via an adhesive layer, ormay simply be in contact with each other without an adhesive layer.Since the radiation detector 10 and the inner wall surface of thehousing 120 are in contact with each other in this way, the stiffness ofthe radiation detector 10 is further secured.

On the other hand, FIG. 14B shows an example of a configuration in whichthe reinforcing substrate 40 is adopted as a top plate on theirradiation surface 120A side of the housing 120. In this case, as shownin FIG. 14B, the size of the reinforcing substrate 40 is larger thanthat of the sensor substrate 12, and an end part of the reinforcingsubstrate 40 protrudes outward from the end part of the sensor substrate12. In the radiographic imaging apparatus 1 shown in FIG. 14B, theradiation detector 10 is housed inside the housing 120 by fitting thereinforcing substrate 40 into an opening portion of the housing 120 thathas an opening shape on a top plate portion on the irradiation surface120A side. In this way, by using the reinforcing substrate 40 of theradiation detector 10 as the top plate of the housing 120, the thicknessof the housing 120, more specifically, the thickness in a radiationtransmission direction can be further reduced, and the radiographicimaging apparatus 1 can be slimmed. Additionally, since the top plate ofthe housing 120 itself is unnecessary, the weight of the radiographicimaging apparatus 1 can be further reduced.

Additionally, FIG. 14C shows an example of an ISS type radiographicimaging apparatus 1 in which circuit units such as the radiationdetector 10, the control substrate 110, and the power source unit 108are juxtaposed in the transverse direction in the drawing. In otherwords, in the radiographic imaging apparatus 1 shown in FIG. 14C, theradiation detector 10 and the circuit unit are disposed side by side ina direction intersecting the irradiation direction of the radiation.

In addition, although FIG. 14C shows a configuration in which both thepower source unit 108 and the control substrate 110 are provided on oneside of the radiation detector 10, specifically, on one side of arectangular pixel region 35, a position where the circuit units such asthe power source unit 108 and the control substrate 110 are provided isnot limited to the configuration shown in FIG. 14C. For example, thecircuit units such as the power source unit 108 and the controlsubstrate 110 may be provided so as to be respectively distributed ontotwo facing sides of the pixel region 35 or may be provided so as to berespectively distributed onto two adjacent sides. In this way, bydisposing the radiation detector 10 and the circuit unit side by side inthe direction intersecting the irradiation direction of the radiation,the thickness of the housing 120, more specifically, the thickness inthe direction in which the radiation is transmitted can be furtherreduced, and the radiographic imaging apparatus 1 can be slimmed.

Additionally, in a case where the radiation detector 10 and the circuitunit are disposed side by side in a direction intersecting the radiationirradiation direction, the thickness of the housing 120 may be differentbetween the portion of the housing 120 in which each of the circuitunits such as the power source unit 108 and a control substrate 110 areprovided and the portion of the housing 120 in which the radiationdetector 10 is provided, as in the radiographic imaging apparatus 1shown in FIG. 14D.

As shown in the example shown in FIGS. 14C and 14D, there are many caseswhere the circuit units of the power source unit 108 and the controlsubstrate 110 are thicker than the radiation detector 10. In such acase, as in the example shown in FIG. 14D, the thickness of the portionof the housing 120 in which the radiation detector 10 is provided may besmaller than the thickness of the portion of the housing 120 in whicheach of the circuit units such as the power source unit 108 and thecontrol substrate 110 is provided. According to the radiographic imagingapparatus 1 shown in FIG. 14D, it is possible to configure an ultra-thinradiographic imaging apparatus 1 according to the thickness of theradiation detector 10.

In addition, as in the example shown in FIG. 14D, in a case where thethickness of the portion of the housing 120 in which each of the circuitunits such as the power source unit 108 and the control substrate 110 isprovided and the thickness of the portion of the housing 120 in whichthe radiation detector 10 is provided are made different, and in a casewhere a step is generated at a boundary portion between the twoportions, there is a concern that a sense of discomfort may be given toa subject who comes into contact with a boundary portion 120B. For thatreason, it is preferable that the form of the boundary portion 120B hasan inclination. Additionally, the portion of the housing 120 in whicheach of the circuit units such as the power source unit 108 and thecontrol substrate 110 is housed and the portion of the housing 120 inwhich the radiation detector 10 is housed may be formed of differentmaterials.

As described above, each of the above radiation detectors 10 comprisesthe sensor substrate 12, and the reinforcing substrate 40. In the sensorsubstrate 12, the pixel region 35 of the first surface 11A of theflexible base material 11 is formed with the plurality of pixels 30 foraccumulating the electric charges generated in response to radiation.The reinforcing substrate 40 is provided on at least one of the firstsurface 11A side of the base material 11 or the second surface 11B sideopposite to the first surface 11A, includes the foamed body layer 50,and reinforces the stiffness of the base material 11.

Since the foamed body layer 50 contains the cells and has a low thermalconductivity, the heat insulating property is high. In particular, in atleast one of a case where the foamed body layer 50 has the closed cellstructure, a case where the closed cells 51A are 85% or more, or a casewhere the sandwich structure is provided in which the foam layer 50A issandwiched between the non-foam layers 50B, the thermal conductivity islower and the heat insulating property is higher.

Therefore, in each of the above-described radiation detectors 10, thebending stiffness is high and the heat resistance can be improved.

In addition, since a subject is disposed on the irradiation surface 120Aside and a radiographic image is captured, the heat of the subject istransferred to the radiation detector 10 through the top plate on theirradiation surface 120A side of the housing 120. For that reason, asshown in FIG. 7A and the like, it is preferable that the reinforcingsubstrate 40 is provided on the irradiation surface 120A side of thehousing 120. In this case, the heat insulating function of the foamedbody layer 50 of the reinforcing substrate 40 makes it difficult for theheat from the subject to be transferred to the sensor substrate 12. Inparticular, in the ISS type radiographic imaging apparatus 1, since thesensor substrate 12 faces the irradiation surface 120A of the housing120, it is preferable that the reinforcing substrate 40 makes itdifficult to transfer the heat from the subject.

Additionally, the circuit unit of the signal processing substrate 300 orthe like generates heat. For that reason, in a case where the circuitunits such as the radiation detector 10, the power source unit 108, andthe signal processing substrate 300 are provided side by side in theincidence direction of the radiation, as shown in FIG. 7B and the like,it is preferable that the reinforcing substrate 40 is provided on theside opposite to the irradiation surface 120A of the housing 120. Inthis case, the heat insulating function of the foamed body layer 50 ofthe reinforcing substrate 40 makes it difficult for the heat from thecircuit units to be transferred to the sensor substrate 12. Inparticular, in the PSS type radiographic imaging apparatus 1, since thesensor substrate 12 is located on the circuit unit side, it ispreferable to make it difficult for heat from the circuit units to betransferred by the reinforcing substrate 40.

In this way, in each of the above radiation detectors 10, the transferof the heat from the subject, the circuit units, or the like to thesensor substrate 12 can be suppressed by the foamed body layer 50 of thereinforcing substrate 40. Therefore, the quality of the radiographicimage obtained by the radiation detector 10 can be improved. Forexample, in a case where heat is transferred non-uniformly in a planedirection of the sensor substrate 12, there is a case where a darkcurrent generated in the sensor unit 34 of each pixel 30 changesdepending on the transferred heat, and image unevenness occurs in theradiographic image. In contrast, in each of the above-describedradiation detectors 10, as described above, non-uniform heat transfer inthe plane direction of the sensor substrate 12 can be suppressed.Therefore, the image unevenness of the radiographic image can besuppressed.

Additionally, according to each of the above radiation detectors 10,since the reinforcing substrate 40 includes the foamed body layer 50 andthe bending stiffness can be reinforced by the foamed body layer 50, theweight of the radiation detector 10 can be reduced without lowering thebending stiffness.

In addition, the configurations of the radiographic imaging apparatus 1and the radiation detector 10, and the method of manufacturing theradiation detector 10 are not limited to the configurations describedwith reference to FIGS. 1 to 14D. For example, in the above description,the so-called indirect conversion type radiation detector 10 comprisingthe sensor substrate 12 formed with the pixels 30 for convertingradiation into light with the conversion layer 14 and accumulatingelectric charges generated in response on the converted light has beendescribed. However, the radiation detector 10 is not limited to theindirect conversion type. The radiation detector 10 may be a so-calleddirect conversion type radiation detector 10 comprising a sensorsubstrate 12 formed with the pixels 30 for directly converting radiationinto electric charges and accumulating the converted electric charges.

Additionally, for example, as shown in FIG. 1 , an aspect in which thepixels 30 are two-dimensionally arranged in a matrix has been described.However, the disclosure is not limited, and the pixels 30 may beone-dimensionally arranged or may be arranged in a honeycombarrangement. Additionally, the shape of the pixels is also not limited,and may be a rectangular shape, or may be a polygonal shape, such as ahexagonal shape. Moreover, the shape of the pixel region 35 is also notlimited.

In addition, the configurations, manufacturing methods, and the like ofthe radiographic imaging apparatuses 1, the radiation detectors 10, andthe like in the above embodiments and respective modification examplesare merely examples, and can be modified depending on situations withoutdeparting from the scope of the present disclosure.

The disclosure of Japanese Patent Application No. 2020-038170 filed onMar. 5, 2020 is incorporated in the present specification by referencein its entirety.

All documents, patent applications, and technical standards described inthe present specification are incorporated in the present specificationby reference in their entireties to the same extent as in a case wherethe individual documents, patent applications, and technical standardsare specifically and individually written to be incorporated byreference.

What is claimed is:
 1. A radiation detector comprising: a substrate inwhich a plurality of pixels for accumulating electric charges generatedin response to radiation are formed in a pixel region on a first surfaceof a flexible base material; and a reinforcing substrate that isprovided on at least one of a first surface side of the base material ora second surface side opposite to the first surface and include a foamedbody layer to reinforce a stiffness of the base material.
 2. Theradiation detector according to claim 1, wherein the foamed body layeris a resinous layer having a closed cell structure.
 3. The radiationdetector according to claim 1, wherein the foamed body layer has aclosed cell rate of 85% or more.
 4. The radiation detector according toclaim 1, wherein an average cell diameter of closed cells included inthe foamed body layer is 10 μm or less.
 5. The radiation detectoraccording to claim 1, wherein the foamed body layer has a multilayerstructure in which a foam layer and a non-foam layer are laminated in alamination direction in which the substrate and the reinforcingsubstrate are laminated.
 6. The radiation detector according to claim 5,wherein the multilayer structure is a sandwich structure in which thefoam layer is sandwiched between the non-foam layers.
 7. The radiationdetector according to claim 5, wherein a main component of a material ofthe foam layer and a main component of a material of the non-foam layerare the same.
 8. The radiation detector according to claim 1, whereinthe foamed body layer has a material containing at least one of foamedstyrene, foamed poly ethyleneterephthalate (PET), or foamedpolycarbonate.
 9. The radiation detector according to claim 1, whereinthe reinforcing substrate further includes a rigid plate that isprovided on at least one surface of a surface of the foamed body layeron a substrate side or a surface opposite to the substrate and has abending elastic modulus higher than that of the foamed body layer. 10.The radiation detector according to claim 9, wherein a thickness of thefoamed body layer is larger than a thickness of the rigid plate.
 11. Theradiation detector according to claim 9, wherein a material of the rigidplate includes carbon fiber reinforced plastic (CFRP).
 12. The radiationdetector according to claim 9, wherein the rigid plate has a punchingstructure having a plurality of holes.
 13. The radiation detectoraccording to claim 1, further comprising: an electromagnetic shieldlayer provided on the second surface side of the base material.
 14. Theradiation detector according to claim 1, further comprising: anantistatic layer provided on the second surface side of the basematerial.
 15. The radiation detector according to claim 14, wherein theantistatic layer is a laminated film of a resin film and a metal film.16. The radiation detector according to claim 1, further comprising: aconversion layer that is provided on the first surface of the basematerial to convert the radiation into light, wherein the pixelsaccumulate electric charges generated in response to the light convertedby the conversion layer, and the reinforcing substrate is provided on atleast one of a surface of the conversion layer opposite to a surface ona base material side or the second surface side.
 17. A radiographicimaging apparatus comprising: the radiation detector according to claim1; and a circuit unit for reading out the electric charges accumulatedin the plurality of pixels.
 18. A method of manufacturing for aradiation detector, the method comprising: providing a flexible basematerial on a support body and forming a substrate in which a pluralityof pixels that accumulate electric charges generated in response toradiation are provided in a pixel region of a first surface of the basematerial; providing a reinforcing substrate that is provided on at leastone of a first surface side of the base material or a second surfaceside opposite to the first surface and include a foamed body layer toreinforce a stiffness of the base material; and peeling the substratefrom the support body.
 19. The method of manufacturing a radiationdetector according to claim 18, wherein the substrate is peeled afterthe reinforcing substrate on the first surface side of the base materialis provided.